drm/amd/display: PSR Refactor

- Refacotr PSR to follow correct module pattern
- fix eDP only working on sink index 0.

Signed-off-by: Sylvia Tsai <sylvia.tsai@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>